Rail clamp



FIG. 1 is a front perspective of the rail clamp;

FIG. 2 is a back perspective thereof;

FIG. 3 is a front perspective view in environment thereof;

FIG. 4 is a front elevation thereof;

FIG. 5 is a back elevation thereof;

FIG. 6 is a left side elevation thereof;

FIG. 7 is a right side elevation thereof;

FIG. 8 is a top elevation thereof; and,

FIG. 9 is a bottom elevation thereof.

The dotted lines in the figures indicate an environment for the rail clamp and do not form a part of the claimed design. 

CLAIM The ornamental design for a rail clamp, as shown and described. 